The inventive subject matter described herein relates to power supply circuits and methods and, more particularly, to sequenced power supply circuits and methods of operation thereof.
A semiconductor device may be supplied with power from an external device. For example, a semiconductor memory device may be supplied with power that enables the memory device to perform read and write operations.
As semiconductor device have become more highly integrated, the operating voltage used in such devices have gradually decreased. An external high voltage may be converted into a low supply voltage for reliable operation of a semiconductor device.
Internal blocks of a chipset may use different power supply voltages. Thus, a power supply circuit may convert an external voltage into at multiple different power supply voltages for the internal blocks. For example, a semiconductor memory device may be supplied with an external voltage and a ground voltage and may generate multiple voltages, such as a reference voltage, a core voltage, a peripheral voltage, and a bulk voltage. Techniques for supplying stable power may protect internal elements of the chipset from sudden power supply and interruption.
Upon power-up of an external voltage applied to a semiconductor device by a power supply circuit, charge may remain in a capacitor of the power supply circuit. Therefore, a voltage supplied to the chipset may not be lowered to a sufficiently low state, even when the power supply circuit is in an off state. This may cause abnormal operation of the semiconductor device.